1. Field of the Invention
This invention relates to releasable locking devices and more particularly to a locking device that prevents the premature coupling of a truck tractor's air braking glad hand to a truck trailer's glad hand.
2. Description of the Prior Art
In the trucking industry, safe and efficient loading and unloading of large tractor trailers is a major concern. Accidents and mishaps to both personnel and equipment are likely to occur by reason of the vehicle accidentally, or even deliberately, being removed from the loading area unless there is an effective way to prevent the premature departure of a tractor's trailer from a loading dock or other designated area.
A limited number of devices have been proposed to deal with the problems of premature departure. The majority of these devices, even though they may perform the function, are beset with shortcomings such as (a) the devices are costly, complex, and are highly susceptible to malfunction due to changes in weather conditions or being struck by the vehicle itself, (b) the locking device is awkward and difficult to operate or install, (c) the device is not capable of accommodating all vehicles of various dimensions, configurations and changing heights due to load variances, and (d) the device is dependent on the presence of a loading dock or adjacent structure.
For example, the majority of the devices require a fixedly attached portion to a loading dock or adjacent structure which includes either an adjustable hook to be attached to a trailer in an operative position or released from the trailer in an unoperative position. The following cases are examples of such prior art:
U.S. Pat. No. 4,264,259 to Hipp discloses a device for releasably locking a parked vehicle against a loading dock. The device includes a pivotally mounted member which is movable between operative and inoperative modes. When in an operative mode, the member has a distal portion thereof in interlocking engagement with the parked vehicle. When in an inoperative mode, the distal portion of the member is disposed in a vehicle release position. A power means is provided for actuating the pivotal member between the operative and inoperative modes. A manual control is operatively connected to the power means. A carriage, having a vertically adjustable first section on which the pivotally mounted member is disposed and a second fixedly mounted on the front wall of the loading dock, is provided.
U.S. Pat. No. 4,443,150 to Hahn et al discloses a device for releasably securing a parked vehicle to an adjacent structure. The device includes a carriage having a first section fixedly attached to the adjacent structure, and a second section adjustably mounted on the first section for movement in a substantially vertical direction. Mounted on the carriage second section is a hook-like member which is movable relative thereto between an operative vehicle -- locking mode and an inoperative vehicle-release mode. Mounted on the carriage second section is a composite lock unit having one portion disposed on the carriage second section and an adjustable complemental second portion mounted on the hook-like member. The portions of the lock unit are adapted to co-act with one another and releasably retain the hook-like member in the operative mode.
A manually activated lift unit is mounted on the carriage second section and is selectively movable independently thereof to effect relative movement of the hook-like member from the inoperative mode to the operative mode only when the unit is pulled upwardly a predetermined distance. A manually actuated release mechanism is adjustably mounted on the carriage second section and, when manually activated in one relative direction, engages and moves one lock unit complemental portion so that the latter assumes a non-retaining position with respect to the hook-like member.
The devices of Hipp and Hahn, et al both require the use of a loading dock or adjacent structure. No device is known that does not require the interaction of a loading dock or adjacent structure with a truck's trailer. Likewise, no device is known that discourages the premature departure of a truck trailer by the disconnection or loss of its braking system.